PROJECT SUMMARY Alcohol use disorder is a major public health issue associated with altered activation of brain stress systems, cognitive deficits, and escalated alcohol drinking. The prefrontal cortex (PFC) is a key structure involved in executive cognitive function and imposing inhibitory control over reward-motivated behaviors. Altered stress responsivity is implicated in the development and maintenance of excessive alcohol drinking, and both chronic ethanol and stress negatively impact PFC function. Cognitive deficits in individuals with alcohol use disorder are thought to hinder successful treatment and contribute to increased risk for relapse. Preclinical studies show that chronic ethanol exposure produces an exaggerated stress response in the PFC that mediates cognitive impairments and escalated ethanol drinking. In the current funding period, we identified chronic ethanol- sensitive proteins and K+ channel genes in the PFC and nucleus accumbens (NAc) of mice and monkeys. We also identified predictive relationships between candidate K+ channel genes and drinking in ethanol-dependent BXD recombinant inbred strains of mice, and pharmacological validation showed that positive modulation of a KCa2 channels significantly reduces escalated drinking in stressed, dependent mice. Moreover, we demonstrated that chronic stress elevates drinking only in ethanol dependent mice and enhances the magnitude of the early component of long-term potentiation (LTP) in the mouse PFC. In addition to the enhanced LTP we observed in the stressed mice, our preliminary data shows that glutamatergic signaling in the PFC is enhanced in macaques following chronic ethanol self-administration. While it is known that chronic ethanol and stress exposure elicit maladaptive plasticity in the PFC, the underlying neural mechanisms and the adaptations in the PFC circuitry induced by ethanol-stress interactions remain poorly understood. To address this gap in our knowledge, we propose three specific aims that will test the overarching hypothesis that disruption of PFC circuitry and plasticity underlies the excessive drinking and cognitive impairments produced by chronic stress and ethanol dependence. Studies in Aim 1 will test the hypothesis that chronic ethanol self- administration and interactions between ethanol dependence and stress produce functional adaptations in the PFC of monkeys and mice. Aim 2 will test the efficacy of drugable proteogenetic targets to reduce escalated drinking in stressed dependent male and female mice. Finally, studies in Aim 3 will test the hypothesis that ethanol dependence and chronic stress produce aberrant signaling in PFC circuitry that contributes to escalated drinking and cognitive impairments. In addition to identifying drugable targets, the findings from these studies will provide data on the temporal aspects of circuit-specific, functional, and morphological adaptations produced by chronic stress and ethanol in the mouse and monkey PFC.